(1) Field of Invention
Animal food trays, particularly adapted for use in conjunction with animal cages, and combinations therewith, especially such animal food trays which are mounted externally of the animal cages and which are instantaneously emptiable.
(2) Prior Art
The testing of various materials for their effects in animals, such as toxicity or the like, is now an established part of our agricultural, pharmaceutical, and environmental picture. Never before has animal testing played such an important part in our civilization. Tests of innumerable types are performed on various species of animals for purposes of determining acute and chronic toxicity, pharmacodynamic activity, antimicrobial activity, antimalignancy activity, teratogenic effect, and for many other purposes too numerous to mention, by many different routes and according to many different test procedures. For this reason, it is necessary to maintain viable animals in cages for shorter or longer periods, as the particular test procedure may require, and to maintain them in healthy condition so that the desired effect upon them can be accurately measured and to avoid undesirable death in a particular colony which would interfere with statistical evaluation of results. To this end, various approaches have been taken to the problem of feeding the caged animals, most of which have involved the attachment of food trays or food containers of one sort or another to the outside of the cage, through which the animals could have access to the food ad libitum, and in most cases these food trays or other containers or dispensers have been hung externally of the individual cage with clamps or extensions protruding from the tray or other container and adapted to engage the mesh of the cage for purposes of maintaining the food container in contact with or in close proximity to the cage to enable access thereto by the animal or animals within the cage. This approach replaced the older approach of placing the food directly into the cage, with its numerous obvious disadvantages. With the development of multiple caging, that is, a plurality of cage units within a single cage, the individual cage units being maintained by means of any of solid or perforated or mesh dividers, some of these food containers became elongated to serve a plurality of the individual cage units simultaneously. The feeding and the food container problem became more complex and involved with the origination of side-by-side caging, that is, cages maintained in side-by-side juxtaposition with respect to each other, and became an even greater concern with the advent of bank caging, in which a plurality of multiple cage units are stacked in banks upon each other, either directly or by means of intervening racks or trays and cooperating vertical support means. In such banks of multiple cage units, it is still not uncommon to see a dozen or so externally mounted food trays per multiple cage unit, attached by means of hooks or the like to the screen of the cage, so that a bank of multiple cages comprising twenty-four twelve-cage units, or two hundred eighty-eight individual compartments, may have up to two hundred eighty-eight individual feeding trays, one per each compartment, or, as is now perhaps more common, forty-eight elongated food trays, each serving up to twelve individual compartments of the cage, and hanging by hooks or the like in the mesh of the cage units at the sides thereof. The problems of keeping the food trays filled with food when desired are substantial, as is well understood by one skilled in the art.
An even greater problem, however, is encountered when it is desired to move an animal cage or a group of animal cages, say two hundred eighty-eight individual compartments, into a test condition or position in which further food intake is not desired, for example, during an inhalation toxicity test, during which entire banks of cages, with animals therein, are placed into a sealed chamber for the testing of materials by inhalation and during which test period no further food intake by the animals is permitted. Other test procedures which require cessation of food intake exist and are known to one skilled in this art. At such time, as will be recognized, it becomes necessary to remove all of the food trays from their position attached to the animal cages, empty them of food, and replace them on the cages, or, alternatively, to store them in some storage place, if available, either with food intact therein, which gives rise to considerable spillage and loss of the food, or after emptying them, which of course requires facilities for storing both food and the trays after having been emptied. The problems involved in such a procedure are apparent, and are even more obvious to one skilled in the art who has found it necessary to carry out such procedure, which of course is extremely time-consuming and uneconomical. It is apparent that a superior food tray for use in combination with animal cages, and particularly one which is readily emptiable upon demand, would serve a great and crying need in this particular art of animal caging, feeding, and testing.